Beer Forum

I mixed up a fresh batch of StarSan with distilled water and after a couple days in my bucket with the lid on it smells slightly of sulphur. It's not strong. pH checks fine. it does not remain in or on anything sanitized with it.

Why does it smell at all? It never has before and I leave it in my bucket for days.

Hmmmm... Star san does contain sulfur in the form of dodecylbenzenesulfonic acid, but I don't know of any reaction that would create free sulfur from that to produce a sulfur smell... as long as the pH is good, it will work. Have you tried rinsing a glass and letting it dry to see if you still detect the sulfur smell? If it doesn't carry over to the sanitized surface, probably no biggie.

Never had that happen.
Can't imagine what would trick out a sulfur smell
Unless yous got's sulfur in yous water ~ ~ ~ ~ ~ ~

It's a christmass mystery.

LAS (linear alkyl sulfonates such as DDBSA) are made by sulfonating an alkyl benzene with sulfur trioxide. Any reaction can proceed in either direction but I would expect the reverse reaction to be much, much, much slower under ordinary storage and use conditions than the forward reaction under the conditions of manufacture. What's weird here is that you never noticed this before. Defective batch? Residual sulfur trioxide left over from the manufacturing process?

The stuff (LAS) does eventually degrade, of course, and we rely on bacteria to do that in sewage treatment plants but, in this application we are relying on LAS + phosphoric to kill bacteria. Interesting question.

Interesting...no smell now that I left it uncovered for two days.